A note on Higgs decays into ZZ boson and J/Ψ(Υ)J/\Psi (\Upsilon)

Rare decays $h\to Z V$ with $V$ denoting the narrow $c\bar{c}$ or $b\bar{b}$ resonances, such as $J/\Psi$ or $\Upsilon$ states, have been analyzed. Within the standard model, these channels may proceed through the tree-level transition $h\to ZZ^*$ with the virtual $Z^*\to V$, and also loop-induced process $h\to Z\gamma^*$, followed by $\gamma^*\to V$. Our analysis shows that, for the bottomonium final states, the decay rate of $h\to Z \Upsilon$ from the loop-induced process is small and the former transition gives the dominant contribution; while, for the charmonium final states, $\Gamma(h\to Z J/\Psi)$ and $\Gamma(h\to Z\Psi(2S))$ induced by $h\to Z\gamma^* \to Z V$ could be comparable to the contribution given by the tree-level $h\to ZZ^*\to Z V$ transition.Comment: 6 pages, 2 figure

Rare WW-boson decays into a vector meson and lepton pair

We have presented a theoretical study of exclusive rare $W$-boson decays, $W\to V\ell\bar{\nu}_\ell$ with $V$ denoting a neutral vector meson and $\ell=e$ or $\mu$, in the standard model. The leading-order contributions to these processes are given by $W\to \gamma^*\ell\bar{\nu}_\ell$ with the subsequent $\gamma^*\to V$ transition. Branching fractions of these decay modes, for $V=\rho$, $\omega$, $\phi$, and $J/\Psi$, respectively, have been calculated and predicted around $10^{-6}\sim 10^{-7}$, which are surprisingly larger than those of two-body hadronic radiative decays $W^\pm\to M^\pm \gamma$ with $M$ denoting a pseudoscalar or vector meson. Thus it is expected that rare $W$ decays into a neutral vector meson plus lepton pair may be the promising channels in future experimental facilities with a large number of $W$-boson events produced.Comment: 8 pages, 3 figures. Some discussions added. Published versio